Means for heating vessls



3 Sheets-Sheet 1 C. O. GLASGOW ET AL MEANS FOR HEATING VESSELS Jan. 2o, 1953 Filed Dec. 26, 1951 M y M wwM M NOM, T

n@ n e5 C0 MJ W rl..

Jan. 20, 1953 Y c. o. GLASGOW ET AL 2,625,915

MEANS FOR HEATING vEssELs Filed Dec. 26, 1951 3 Sheets-Sheet 2 Clarence 0. Glas ow gf o 8 BY Joseph L. Ma er TTRNEYS Jan. 20, 1953 c. o. GLASGOW ET AL 2,625,915

MEANS F OR HEATING VESSELS Filed Dec. 26, 1951 3 Sheets-Sheet 3 E E l@ INVENTOR Clarence 0. Glasgow BY Joseph L. Maher ATTORNEYS Patented Jan. 20, 1953 UNITED STATES PATENT GFFICE MEANS FOR HEATING VESSELS Clarence O. Glasgow and Joseph L. Maher, Tulsa, Okla., assignors to Nationalv Tank Company, Tulsa, Okla., a corporation of Nevada 6 Claims. 1

This invention relates to new and useful improvements in means for heating Vessels.

The structures disclosed in this application are similar to those disclosed. in our co-pending applications Serial No. 775,119, now Patent No. 2,579,184 issued December 18, 1951, and Serial No. 775,120, both filed September 19, 1947, and reference is made thereto. Reference is also made to our co-pending application Serial No. 257,884, filed November 23, 1951.

Heretofore, many methods for heating vessels, such as tanks, have been utilized in the petroleum industry, since it is often necessary to heat the contents of settling orv storage tanks as well as the iiuids passing through emulsion treaters and other types of treating equipment. While the present invention is directed primarily to use with emulsion treaters and is adapted to overcome a large percentage of the difficulties encountered in such use, it may also be employed with advantageous and desirable results in other instances, such as in iiow heaters and settling tank heaters. The invention is not to be limited to a specic use since its new and novel principles may be followed in a multitude of applications wherein uniform heating with substantial freedom from undesirable effects is desired, such as preventing formation of scale while heating of fluids containing large amounts of solids.

Various solutions to the problem of providing suitable vessel heaters have been developed including the injection of certain chemicals to prevent scaling and corrosion as Well as provision of zinc and other metals or dissimilar metals in combination Within the vessel. Also the use of corrosion-resisting steel alloys has been practiced but obviously, the expense involved in this method is usually prohibitory and only the corrosion problem is solved. Where steam is available in suiiicient quantities, steam heaters or coil bundles for steam have been used to advantage. However, neither of these alternatives is satisfactory for isolated vessels, or for locations where steam is not available. Manifestly, the provision of a boiler for the supplying of steam merely to heat a single vessel is not feasible, particularly on account of the unusual radiation losses, and a boiler is practical and economical only if insulated at considerable expense and requires constant and separate attention as well.

It has been the practice heretofore to employ a simple gas-fired heater which extends into the interior of the vessel and heats the contents thereof by direct thermal conduction from the combustion gases through the wall of theuheater to the liquid within the vessel, and without radiation losses therefrom. Necessarily, the well temperature of the heater is high an-d this contacting of hot metal with a corrosive liquid, such as crude petroleum, may and frequently does, create an extremely severe scaling and corrosion problem. There are almost invariably hot spots in the wall of the heater and additionally accelerated scaling and corrosion occurs at these points. Consequently, such heaters rapidly deteriorate and must be replaced within a relatively short period. And. also, when and as such liquids are heated, usually a large amount of precipitate in the form of scale is formed and attaches itself to the outer wall of the heater and continues to build up until it becomes so thick that it is impossible for the heat to -be transferred through the metal and the scale to the uids and consequent failure of the heater occurs due to melting.

Since many vessels, especially in the petroleum industry, are located at isolated points, the usual more elaborate heating procedures are not usable. As many, or most, of these points have natural gas, or other fuel, readily available, it is an obvious step to utilize this fuel for heating purposes. However, the severe corrosion and scaling problems set forth hereinbefore have rendered this expedient unsatisfactory in many cases. In addition, the uid being heated is usually adversely affected by the high temperature of the heater, due to the eifect'of higher temperatures causing an unusually high release and consequent loss of valuable components which would not be evolved when using the method herein described. This is especially true when crude petroleum would make up a part of the fluids being heated. The hydrocarbons present in such iiuid are broken down or cracked to some extent in the high temperature lm of fluid which encases the heater. Thus, gases are evolved which otherwise would not be lost, and the precipitate tends to coke and to partially cover the heater itself with a carbonaceous deposit. Fluids having material in suspension or solution are apt to deposit this material on the heater as said fluids are subjected to the excessive temperatures. Often, iiuid systems including several liquid phases with gases and-solids dissolved therein must be heated, as in petroleum emulsion treaters. These systems verge on instability and must be carefully processed to permit only the desired stratification and precipitation to take place. Usually, the ordinary heater causes excessive precipitation and degasication in such a system so that ineicient results are obtained. The loss of volatile componente and cracking of other components represent a needless but heretofore unavoidable waste. At the same time, the deposit of coke and other solids on the heater hastens its deterioration while impairing its heating eiciency.

Another undesirable feature of ordinary heaters stems from the excessive degasication along with the volatilization of oil and water or other components caused by the contacting of the hot heater surface by the emulsion or other fluid being processed. The gaseous vapors thus generated naturally course upwardly through the body of fluid being heated and create considerable turbulence which is undesirable in itself besides the loss caused by the volatilizaticn of com.- ponents which otherwise could be retained and conserved.

The turbulence caused by bubbling and excessive localized heating stirs and agitates the body of fluid being heated, and destroys the quiescent state often .sought to be maintained. This is particularly true in petroleum emulsion treaters wherein stratification of the separated components `is usually essential to satisfactory operation. Turbulence delays such stratification and creates obvious impedances to proper treater functioning.

The uniform and moderate heat applied through the present method also reduces and substantially limits thermal convection currents within the Vessel tothe unavoidable minimum which ,dependaY of course., onthe degree of heat necessarily required .to beemployedin each. para ticuiar application. suchconvection currentsfare often quiteviolent in themselves and impail'to a considerable extent the desired settling and stratication often desired. Hence .the ordinary direct-contact heater creates unwanted `turbulence by both vaporization and excessively strong convection currents.

In addition to the delaying of stratification, such turbulence also often causes or increases the decomposition of unstable salts, such yas bicarbonates, decomposition which otherwise would not occur. And, in general, the precipitation ofvarious solids and other undesirable results ensue. Therefore, in many instances, all avoidable agitation and stirring of the fluid being heated is to be eliminated insofar as possible. heating method and structure accomplishes: this by uniform, moderate, controlled heating.

The present invention overcomes substantially all of these diiiculties by means of a heat-ex.-

change medium which is relatively inert and serves to protect the fluid `being heatedV against the application of excess-ive heat, while also pro,- tecting the hot walls of the heater from accelerated scali-ng and corrosion.

There are many reasons why it is vdesirable -to have such a heater so constructed as to be insertable as a unit into the interior of the vessel to be heated. One reason is that a unitary str-llc,- ture is achieved which maybe shipped and inf stalled as substantially one main elerirlent4 and requires only (me foundation yorbase.- AAnother is. that what would otherwise be heat .losses from the heater are absorbed by the liquid in the-vessel rather than being dissipated to the atmosphere. Still another is that materials are conserved because it is not necessary to provide a separate housing and separate insulation for the heater, along with connecting pipes and the like which are subject to leakage, heat dissipation, and corrosion.

The present l It is therefore the principal object of this invention to provide an improved heating means which substantially eliminates the undesirable consequences of contacting the combustion chamber walls of a heater with a liquid which is corrosive, unstable, and/or has constituents which tend to decompose in the Vpresence of excessive heat.

Another object of this invention is to provide an improved, internal vessel which is adapted to be positioned within the vessel containing the liquid to be heated, but which is readily available and/or removable for inspection, repair or replacement.

Another importantobject of the invention is to provide an improved system for heating a body of liquid within a vessel wherein a body of heating fluid `is enclosed within the body of liquid and heated whereby the body of liquid is indirectly heated through the body of fluid.

A further object of the inventionl is to provide an improved heater ofthe type described utilizing steam or other suitable heating mediums for conducting and transferring heat from the heater to any desired point or points in the vessel containing the liquid to be heated, whereby heater corrosion and hot fluid lm problems are substantially eliminated.

Yet another object of the invention is to provide an improved, internal vessel heater particularly adapted for use in vessels through which fluids to be heated are flowing, said heater providing increased heating area and circuitous paths which the fluids' may follow for improved, controlled heating; and wherein means Vare provided for drawing oi a heat exchange medium from the heater and directing the former to any desired point in the vessel for additional or supplemental heating of the fluids.

A still further object of the invention is to provide an improved internal heater especially desirable for use in petroleum-containing vessels such as emulsion treaters, which furnishes ample heat for carrying out emulsion-breaking or other operations, but which does not subject the petroleum to temperatures in excess of the point at which decomposition and other undesirable results, such as turbulence, become of Consequential magnitude.

Another object of theinvention is to provide an improved internal, vessel heater for use in emulsion treaters from which the separated water is to be conducted through a filter and/or to a disposal well, wherein the emulsion. being treated is heated in accordance with the lreq1 iiren 1e. r 1ts of that particular emulsion, and is not heated at any point above the critical temperature or temperatures at which precipitation becomessubstantial so as to tendY to clog the pores of the filter and/or the disposal well.'

A particular object of the invention is to pro,- vide an improved internal, vessel heater in the form of a low-pressure boiler affording the advantages of steam heating of the vessel but avoiding the expense, complexity and attention. involvedin utilizing the ordinary steam boiler.

Another object of the Vinvention is to provide an improved internal vessel heater having a heater drum and a steam drum insertable as a unit into an emulsion treater or other vessel through which fluid passes to be heated or to be heated and otherwise processed; and wherein means are provided for preheating the incoming fluid before the latter enters into the principal heating zone or area.

A still further object of the invention is to provide an improved heater for emulsion treaters having a main heating element and an auxiliary coil connected to the heater for drawing off a heat exchange medium therefrom, said coil being positioned so that the incoming iluid flows thereover and therethrough and is preheated before contacting the main heating element,

In this application and the claims appended thereto a number of defined terms will be used for the sake of simplicity.

The terms heat-unstable liquid and heatunstable ui will be used to designate any liquid or fluid which tends to deposit scale or cake on an excessively heated surface, to display corrosive properties, to decompose in the presence of heat, to lose components by vaporization in the presence of heat, or from which solids may precipitate in the presence of heat, or which may undergo other undesirable changes in the presence of elevated temperatures such as petroleum, petroleum emulsions, salt-bearing liquids such as Water, and like fluids.

The terms heat-stable liquid and heatstable fluid will be used' to designate -liqulds or fluids which do not deposit scale or become corrosive Within reasonable temperature limits and which exhibit a substantial minimum of undesirable or harmful properties when in contact with a hot surface, such as hot metal, within the range of ordinary llame temperatures, examples being fresh water, ethylene glycol, commercial heat-transfer fluids, andl thel like.

A yconstruction designed to-carry out the invention will be hereinafter 'described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to thel accompanying drawings, wherein examples of the invention are shown, and wherein:

Fig. 1 is a vertical, longitudinal, sectional view of a heater constructed in accordance with this invention,

Fig. 2 is a vertical, transverse, sectional view taken on line 2-2 of Fig. 1,

Fig. 3 is a vertical, transverse, sectional view taken on line 3-3 of Fig. 1,

Fig. 4 is an elevation of the burner end of the heater,

Fig. 5 is a vertical, sectional view of an emulsion treater showing one adaptation of the heater, Y

Fig. 6 is a vertical, sectional view of an emulsion treater showing a second adaptation of the heater,

Fig. 7 is a vertical, sectional view of an emulsion treater showing a third adaptation of the heater, i

Fig. 8 is a vertical, sectional view of Vthe lower portion of an emulsion treater showingva modifcation of the heater utilized in a manner simi lar to that shown in Fig. 6, and

Fig. 9 is a vertical, sectional view of an emulsion treater showing another modification of the heater utilized in a manner similarto thatshown inFigV'I. l f

This application is a continuation of our copending application, Serial No. 775,118, filed September 19, 1947, now abandoned.

In the drawings, .the numeral I0 designates a vessel or container through which flows or in which is disposed a heat-unstable liquid which is to be heated. This invention Vvdoes not contemplate primarily the heating of liquids within the vessel to temperatures in excess of 250 F. However, higher, and especially lower, temperatures may be obtained and employed in accordance with the heating problem at hand. Therefore, specific reference to operating temperatures has not been made.

Nor is the invention to be limited to specific heat exchange mediums or heat-stable fluids (although fresh water is chiefly used), or to certain liquids to be heated. This method of and means for-heating is particularly adaptable to the petroleum industry wherein is processed and handled a raw product, fluid in nature, and of widely variable composition; a product which is often corrosive and is relatively unstable. Obviously, this invention is of great benefit under such circumstances. Nevertheless, there are many other applications readily apparent, possibly of equal importance and certainly of equal benefit and success.

For the purposes of illustration, the invention will be described largely with reference to use in petroleum emulsion treaters. And, to avoid unnecessary repetition, the various other uses of the invention will not be pointed out at each pertinent phase or point of the description. However, it is to be kept in mind throughout that reference to emulsion treaters is illustrative only.

Proceeding now with the description of a specific embodiment which incorporates the novel features and principles of this invention and illustrates this new method of heating, the vessel I0 receives a heat generator or unit A through a flanged opening I I in one side wall of the vessel. The heating unit has a casing which includes an upper or vapor chamber or drum I2 and a lower or liquid chamber or drum I3, both drums being in the shape of elongate cylinders or receptacles having their inner ends closed by suitable dished plates I4 and I5, respectively. The drums are disposed horizontally within the vessel and have their longitudinal axes alined parallel to one another in a vertical plane. The outer end of the upper cylinder is closed by beingI welded to the upper portion of a vertical plate I6 of such size and shape as to cover the flanged opening II, said plate being secured to the flange by suitable bolts I'I. The plate I6, thus affixed in position closing the opening II, supports the upper drum I2 in a proper horizontal position with the vessel I0.

The lower drum I3 has its outer section I8 extending through the lower portion of the plate I6 and projecting outwardly therebeyond. The drum is welded, or otherwise suitably secured, to the plate so as to be supported thereby. Thus, since both the upper and lower drums are carried by the plate I6 and constitute the major portion of the-heating unit, the latter may be readily removed for servicing or inspection by simple removal of the plate.

An annular, external flange I9 is provided on the extreme outer end of the outer section I8 of the lower drum for securing a boiler unit B. The boiler unit comprises an elongate heat generating or combustion chamber or tube 20 having a suitable burner structure or other heat supplying means 2| secured to its outer, open end and its opposite end closed. A plurality of tubular elbows 22 are connected into the combustion tube near its closed end and communicate with the interior thereof. The elbows are arranged in spaced and staggered relation in two circumferential rows encircling the combustion tube, and project radially therefrom with their outer ends andere directed' :toward :the burner endl lof .the tube.; suitable vv-elongatefre tube-or yconduit 23 is welded orfotherwisesecured tothe outer end of eachof the `elbows 2.2, said tubes extending' in parallel relation to and adjacent the combustion tube20. Thus, dame and combustion gases may travel from the burner structure .25, through the combustion tube 2li and the elbows 22 into the `nre tubes 23, and therethrough to a pointradjacent the `burner end of said combustion tube. The re tubes, therefore, may be described as return fire tubes.

vvThe combustion tube carries a. relatively Wide external, annular flange 24 at a point spaced a shortV distance from the burner structure. The flange is substantially equal in diameter to the flange .I3 carried by the lower drum I3 although the :combustion tube is less in diameter than said drum. A plurality of spaced, radially-offset openings 25 are provided in a concentric circle yin the flange 2.5i, and receive the outer ends of the re tubes 23. The joints between the re tubes, the elbows, andthe combustion tube, are made fluidtight `by welding or `other suitable means. That portion of the boiler'unit from the flange 24 inwardlyis thus fiameand fluid-tight.

A cylindrical smoke box 26, having one end open, Aencircles the outer portion ofthe .combustion tube and has its open end abutting and joined to the flange 24. The diameter of the smoke box is such as to place the open outer ends of. the re vtubes therewithin whereby the combustion gases are lconducted into the interior vof the box. The combustion tube extends through the outer end wall of the box and projects therebeyond, the burner structure 2i being connected into the'projecting portion of the tube exteriorly of said loo-X. A suitable smoke stack or flue 21 conducts combustion gases upwardly from a nipple 28 communicating with the smoke box, and may be of any desirable style or structure. The stack terminates, ordinarily, slightly above the upper end of the vessel Ill and may carry a downdraft preventer (not shown).

The entire boiler unit B is insertable as a onepiece structure (normally without the flue 2l) into the lower or fluid drum i3. The ange 24 abuts the flange i9 and is secured thereto by bolts 2e, thus rigidlysupporting and maintaining the boiler unit in its proper position. The combustion tube 2Q of such length as to terminate short of the inner end wall i ofthe lower drum thereby affording a small spaceiadjacent said end wall, and the over-all diameter of this tube along with the surrounding re tubes 23 is less than the internal diameter of the lower drum so that an annular heating space is provided between the 'boiler unit and the inside walls of the drum. The boiler unit is thus removable and replaceable as an integral element for servicing or inspection, and the maintenance of the entire heating unit A in proper operating condition is facilitated and considerably simplified.

The burner structure 2i receives suitable `fuel or fuel and air connections .33 for supplying any desirable combustible substance Vto the former. Usually, of course, fuel oil or gas will be utilized, and especially the latter in installations in the petroleum industry. However, this invention also contemplates the use of other means of heating such as electricity or high temperature heat eX- change fluids of an organic nature. Suitable control means such as a valve 3i or automatic, temperature-controlled devices (shown in laterdescribed illustrationslmay be Yemployed to control .and 'regulate VAthe `'heai'f'output lof ithe-=boiler unit, orto-maintain 'a certain portionzor portions ofthe vessel Ill at set temperatures. vIn the latter case, suitable temperature-responsive elements may be positioned in the vessel at suitable points and-operatively connected to the burner control means. Y

A fluid conductor in the form of a short nipple 32 extends vertically'between the upper and'lower drums I2 and I3, being connected into the bottom and top walls respectively thereof, by welding .or other suitable means. The conductor v32 is positioned near the outer ends of the drums while a similar, smaller conductor 33 depends from the lower wall of the upper drum near its inner, closed end I4. The conductor 33 extends downwardly through the upper wall of the lower drum into the Vspace between the inner end of the'combustion tube and the end wall I5 Yof said lower drum. This 'latter conductor terminates a :short distance above the bottom wall ofthe lower 'drum' vso vas to direct fluid adjacent'the lower side of the boiler unit B, as will be more fully 'described hereinafter.

All the connections'andjoints between the conductorsv 32 'and 33 andthe upper and lower-drums are' fluid-tight so that the drums are interconnected in sealed relation with their interior portions in substantially direct communication. The conductors also supplement theplate IS' in linking the drums together structurally into an integral 'rigid elements forming a portion ofthe aforesaid heating unit A. 'I'his unit is Areadily removable Awhen Yso desired, by disconnection of thebolts I'I, whereby the' entire unit may easily be serviced, repaired or replaced with a minimum of difficulty and labor, and whereby properv inspection is facilitated and encouraged due to the ease of such inspection. Obviously, replacement of either the entire heating unit A or the boiler unit B is greatly simplified, the latter especially so since draining of the vessel I0 is not required for such replacement.

However, the need for replacement of either unit is seldom encountered `by reason of the other desirable features of this invention.

A suitable heating or heat transfer medium is contained within the drums I2 and I 3. This medium may be fresh water, or various other vapor-forming substances or any other heat eX- change fluid having the desired physical and chemical characteristics. Chemical inertness or non-corrosiveness, high latent heat of vaporization or Ahigh specific heat, and good heat conduction are, of course, especially to be sought in such a fluid. Although fresh water is widely used, the invention is not to be limited to such use, as any of the well known fluids or mediums may be and are used in accordance with the requirements of the specific conditions at hand.

The heating medium, or heat-stable fluid, fresh water as an example, is disposed within the upper and lower drums and carried at a level in the lower half of the upper drum. Again, any desired level may rbe employed, the usual requirement of covering the re tubes 23 being observed. The plates IB and the flange 24 re'- tain the fluid within the drums as well as seal the latter against moderate pressures. A fluid level glass or gauge 34 is connected into the platel to indicate the level of the fluid within the heating unit, and a suitable lling connection 35 is also carried by the plate to permit addition of heating fluid to said unit. Safety connections such as pressure relief valves, tem- `undesirable or harmful conditions.

contributed by such a fluid.

perature controls, and the like, may be connected into the unit at any desired points. A drain tube 36 extends from the lower wall of the lower drum for removal of the heating fluid.

The structure described, while simple in operation, possesses many advantages and features not heretofore supplied by previous heaters. The combustion tube and the fire tubes, being surrounded by a blanket of non-corrosive heating fluid, are protected against scaling, along with decomposition and accelerated rusting and other In addition, since the tubes are immersed in a uid selected for its efficacy as a heat exchange medium, the former may operate more efficiently due to the improved heat transfer conditions inherently Hot spots are reduced in size and intensity, and a general over-all reduction of scaling and the like, and of high film or heat transfer resistance, along with an increase of heating rate and efficiency results. At the same time, turbulence and vaporvization are minimized because of the uniform vdensity of the medium or fluid is increased and it seeks the level of the lower drum bypassing downwardly through the conductor 33 to the lower portion of the lower drum I3 wherein it is again heated by the boiler unit. Thus, a continuous heating and cooling of the fluid occurs, setting up a thermal convection circuit or circulation of the heated medium into the upper drum and a return of the less-heated medium into the lower drum'. Both drums thus may be called conductors or enclosures insofar as their conducting of the heat exchange fluid is concerned. V

`Of course, both drums are relatively hot and within the same temperature range so that there 'is a constant transfer of heat to the contents of the vessel l from both drums. The overfall quantitative transfer of heat approaches the input of the burner unit since the heat radiation from the heating unit, which is normally lost by dissipation to the atmosphere from the unit and the pipes connecting it to the vessel, is instead absorbed by the contents of the vessel. The units of heat which escape through the stack represent a relatively small percentage due to the low specific heats of the combustion gases and the eicient heat transfer afforded by the nre tube structure.

As pointed out before, the nature of the heating medium protects the boiler unit as well as enhances its thermal eiciency. The utilization of this fluid as an intermediate conductor of heat also protects the liquid contained within the vessel IU and provides a more desirableand uniform mode of introducing heat into said vessel. Since the hottest portion of the heating medium will not be at a temperature greatly in excess of the boiling point of the medium and the coolest portion of said medium will not be at a temperature greatly therebelow, the entire exterior walls of the unit will be kept at a substantially uniform `temperature with no hot spots or locally-increased rates of heat transfer. Therefore, the objectionable features of ordinary heaters set out hereinbefore are substantially eliminated. Local ized coking or scaling on the outside of the heater, and decomposition, along with excessive volatilization, of the vessel contents is rendered negligible if not prevented entirely.

It will be readily seen that this heater is particularly adaptable to emulsion treaters of the type wherein the emulsied fluid flows through a vessel in which it is heated to facilitate breaking of the emulsion and its separation into its normally immiscible phases, along with the actions of reduction of excessive gaseous content and stabilization of the uids produced. Such emulsion is preferably introduced below the heating unit A and allowed to new upwardly, by reason of its density or gravity, through the body of salt water normally present in such treaters. In passing over and around the drums I2 and I3, the emulsion is heated to the point at which it readily straties, under the influence of the conditions present, into its plurality of immiscible components, the latter seeking their own level by reason of their differences in gravity. Thus, oil, relatively water-free, rises to the upper portion of the vessel and the water (usually salt water) settles or remains in the lower portion of the vessel. Suitable and usual connections (later described) maintain the oil and water phases at the proper levels by removing these components separately in accordance with the quantities thereof introduced in the influent emulsion.

Of course, the entire contents of the vessel will be heated or warmed because of the immersion of the heating unit therein, and especially the body of salt water which is in immediate proximity to the heating unit. Obviously, a portion, which may be considerable, of the heating of the incoming emulsion is carried out or effected by this body of heated fluid through which the emulsion passes, so that a situation obtains wherein the emulsion is constantly drawing heat from said body of fluid and by direct Contact, from the heater unit, while the boiler unit B, through the convection circulation of the heating medium within the heating unit, is constantly supplying heat to the emulsion and restoring or maintaining the heat content of the heated body of liquid external of said heating unit. And this exchange and distribution of heat is carried out without permitting .any of the Vessel contents to come in Contact with an excessively heated surface or allo-wing the relatively hot combustion and fire tubes of the boiler unit to be subjected to the action of other than relatively inert, non-corrosive fluids.

The desirable and advantageous results are manifest. The many contributory and componental benets cumulate in two main and irnportant benets, namely, a greatly increased life and maintenance of operating efficiency for the heating unit, and freedom from deleterious effects upon the liquid being heated within the Vessel lll.

In Figs. 5 through 9 of the drawings are shown various applications of this heating method and structure to petroleum emulsion treaters.

The treater shown in Fig. 5 includes the usual tank 40 having a, preliminary separation charnber lll, which may be of any suitable type or structure, disposed in its upper portion. The heating unit A is carried in the lower half of the tank and is provided with any desirable type of 'gesamt pipe coil 42 within the upper drum I2. An emulsion inlet pipe 43 extends upwardly to the chamber 4I, the coil 42 beingY connected into said pipe whereby influent emulsion passes through the former. Thus, the incoming emulsion is heated by the hot liquids and vapors within the upper drum and enters the chamber 4I in a somewhat warmed or heated condition. For this reason, the preliminary separation of the emulsion into its constituent components along with the coalescing of free water and removal of excessive gas is greatly enhanced and a larger proportion of such separation occurs prior to the introduction of the emulsion stream intothe lower portion of the tank. In this manner, the load placed on the lower portion of the tank is reduced and separation and stratication of large portions of the emulsion takes place almost immediately upon its entry into said lower part of the tank. The heat available from the body of salt water and the heating unit is thus utilized to a large extent to heat and break the tighter portions of the emulsion since the heating unit is not encumbered and hampered by the presence of large quantities of loose emulsion. The latter, having already been separated to a considerable degree, enters as relatively distinct oil and water phases which pass rapidly to their respective levels in the tank. This rapid flow is engendered by the comparatively sharp diierence in the gravities of the oil and water. The as yet unbroken emulsion has a more intermediate gravity, usually nearer that of water than that of oil, and therefore tends to pass upwardly over `the drums I2 and I3 at a relatively slow rate whereby its heating, and subsequent breaking or separation, is greatly facilitated. As it separates, -its components, of course, move more rapidly toward their proper levels. In this manner, the output of the heating unit is directed toward more eicient and certain results, and the over-all eiliciency and eicacy of the emulsion treater is enhanced.

The emulsion, after preliminary separation in the chamber 4I, passes downwardly througha conductor 44 to a spreader 45positionedbeneath the heating unit A. Because of its gravity, the emulsion flows upwardly throughthe. body of heated water present, around the drums I2. and I3, and is properly broken and separated. Oil is taken off near the upper end of the lower portion of the tank by a pipe 46, While water is drawn oi from the lower end of the tank by a water leg 4l. The structure of the water leg is such as to -maintain the desired water level within the tank and acts, through the well-known principles of syphons, to remove water only as it is introduced by the inuent emulsion. The body of heated Water is thus kept at a substantially uniform level at all times.

Suitable pressure equalization lines and pipes 48 connect the various outlets and compartments of the tank so that the gravity and syphon flow by which the tank operates, is not hindered or adversely affected. A-small gas scrubbing chamber 49 is provided inthe upper'end of the chamber 4I for removing entrained and/or readilycondensable liquids from eiuent gas being conducted from the tank.

A second application of the heating unit is illustrated in Fig. 6 of the drawings. This emulsion treater includes a tank 50 having the heating unit A positioned in its lower portion adjacent the bottom thereof. The petroleum stream carrying emulsied components enters through "al vertical Hume 5I extending tiornthe upper-*end of the tank toa spreader 5 I" positioned below the heating unit. An elongate helical heating coil 52 isdisposed within the ume for heating the-inuent emulsion forthe purposes and benefits set out hereinbefore. The upper end ofthe vcoil is connected through a riser pipe 53 to the upper side of the upper drum I2, while the lower end of the coil is connected to the bottomY ofA the lower drum I3. This arrangement permitsl a thermo-syphon action toy be set up, which circulates the heating medium or'fluid through` the coil 52 for heating the incoming` 'petroleum stream, thus extending the thermo-syphonciriculation of the heating unit A to include. the coil.

A suitable control means or valve 54 isfc'onnect'ed into the riser pipe 53.-.and isadapted toibe actuated or controlled by a temperature-responsive element 55 which may be of `any desired type. The element 55 is normally situated 'atsome-point within the tank sol as to regulate Vthelpas'sageoi heating iiuid through the coil 52. Assis shown in Fig.- 6, the element may be mountedl withinthe ume below the coil, but other suitablepoints may be used.

The emulsion, after. being heatedpinits passage through the ume 5I whichallows partial sepa:- ration and/or agglomeration of theiemulsiied constituents, enters intofthe lower part 'ofthe tank 50 and is heated therein vby the body'of `hot salt Water and the heating unit. `After separation and stratification; the oil isA draw-n .off through a pipe 5E which, like the pipe 46issituated near the top of thetank and maintainsa proper oil levelwithin the latter.v 'A water'legrlil, similar to the water leg lll,y insures a proper water level within the tank andfprovides for 'discharge of excess water therefrom. Suitable conductors 58 equalize pressure'between the water leg, the flume, and the tankY so that any evolved rCir-'refleased gaseous components are removed through a gas connection 519. Ai filling connection `(not shown) along with suitable gauge meansand safety devices (not shown) maybeiconnectedinto the heating unit or thecoilrat any desired point or points.

The operationof 'this latter typetreateris sub1- stantially the same as that set forth in connection with the rdescriptioniof` th'ezform'shewnin Fig. 5 and wi'll'n'ot berepeat'edl'here. Sufficefitftosay thatv the Vadvai'itageou's and desirable results. be"- fore recited, also' obtain intthis form, and in addition, means are providedffort'corrtrollingthe heating of Ythe. iniiuent emulsion 'with' its1obvious`- 1y bene'cent effects.

rA, third form ofV an femulsion `treater applying the principles of this heatingfmethodiisl'shownfin Fig. 7. This formisvery vsimilar to theifrm shown in Fig. 5, but Aprovides for.contr'olroffA the emulsion pre-heating. 'Thefstru'cture includesza tank 65 with the heating carriedzthereiii. A preliminary separation ohamberl is disposed at the upper end of the tankfand'receives the emulsion stream directly through anI inlet pipe 62. A suitable heating coil 63 ismounted within the chamber 6I land 'connected'through riser pipes 64 to the upper and lower sides of the upper 4and lower drums I2, and I3, respectively. A thermosyphon connection is thus providedfwhich permits natural circulation of the'heating'fluidr` from the heating unit through the coil to'heat the contents of the chamber 6I. The emulsion is thereby heated prior to its introduction intov 'the main treating chamber of the tank with the'desired'results which have been set out.`

'.13 A flume 65 conducts the emulsionstream down- Wardly through the tank to a spreader 66 positioned below the hea-ting unit.v An oil outlet 61 and Water leg 68 function as before' described, and suitable gas equalizing and discharge connections 69'provide for adequate adjustment and disposal of this component. Filling and safety devices are connected into the heating unit or the coil at any desired point or-points.

A control valve element 1I is connectedinto the coil 63 near the upper end of one of the pipes 64 and is operatively linked to a temperature-responsive element 12. The latter element may be situated wi-thin the chamber 6| or at any other suitable point to control the heating of the'emulsion inthe proper fashion.

In Fig. 8, a modification of the treater shown in Fig. 6 is illustrated. This modification differs only in the structure of the upper drum l2. For the purpose of increasing the heat exchange area offered by the latter drum, a, plurality of transverse conductors 13 extend thereacross. The conductors are disposed at substantially 45 angles and communicate with opposite exterior sides of the drum so that the fluid within the tank may pass therethrough and be heated by the contents of the drum. The connections between the ends of the conductors and the drum wall are huid-tight whereby no commingling of the tank contents and the heating medium can take place. Increased heating area and increased thermosyphon paths are provided by this structure.

The conductors 13 may be arranged in any desired fashion. However, a particularly suitable structure has been found to comprise two rows of conductors disposed at right angles in alternate relation, with each row. being positioned at substantially a 45 angle with respect to the horizontal. Fluids are thus heated in passing upwardly through the conductors, and a plurality of heating channels or circuits is afforded.

Fig. 9 represents a modification of the treater shown in Fig. '1 and is similar in most respects thereto. This last treater employs a different form C of the heating unit A in that the upper drum I2 is eliminated. The heating medium or fluid level is carried in the upper portion of a drum 80, very similar to the lower drum I3, and riser connections 8l are made to the upper and lower sides of the lower drum. A coil 82 is carried in a preliminary separation chamber 83 disposed at the upper end of the tank 84.

The drum 80 receives the boiler unit B and may have suitable filling and/or safety fittings connected thereinto. In the illustration in Fig. 9, such connections 85 are made at the upper end of one of the riser pipes 8l with a liquid level guage 86` being connected into the drum at a lower elevation. In all other respects, this latter treater is substantially identical to the treater shown in Fig. '7, and has a flume 81 and a spreader 88, with separated oil being drawn off through an outlet pipe 89. A Water leg 90 removes separated water and is connected by suitable equalizer lines 9| to the compartments of the tank and a gas discharge line 92. A temperature-responsive element 93 controls heating by the coil 82.

This modified heater unit C may, of course, be utilized with the other applications described hereinbefore. Its primary use is in instances wherein less intense heating is required, but it may be used substantially interchangeably with the heater unit A with the same beneficial results.

In all of the described modifications and ap- 'plications the conductors and lflumes, such as vand the cumulative effect of all the various desirable characteristics hereinbefore set out is vto provide a treater having a high emulsion treating capacity in comparison to its size and fuel requirements. This important end-result is contributed to by all the advantages and features incorporated into the heater units as well as the treater structures, and is a direct result of this improved heating method. Indeed, throughout the various examples the efficiency and increased working life obtained, along with non-impairment of the liquid being processed, stems directly from this new method and structure for heating.

What we claim and desire to secure by Letters Patent is:

1. The combination with a liquid containing vessel having an opening within one wall, of an internal heater including, a heater casing projecting into the vessel through said opening and being removably secured in such position in the body of liquid within the vessel, a combustion tube removably secured within the casing having its inner end sealed and its outer end projecting from the casing and the vessel, return fire tubes extending from the sealed end of the combustion tube within the casing and extending along the interior of the casing to the outer end of the combustion tube, a smoke box enclosing the outer ends of the fire tubes, and a heat exchange fluid within the casing enveloping at least a major portion of the combustion tube and the fire return tubes, the combustion tube and the fire tubes transferring heat to the heat exchange fluid and thence to the liquid within the vessel.

2. The combination with a liquid containing vessel having an opening in one wall, of an internal heater including, a heater casing having upper and lower chambers disposed within the vessel and immersed in the liquid contained therein, connections betwen the chambers for thermo-siphonic fiow, a heat exchange fiuid contained within the casing, said casing being so dimensioned to pass readily through the vessel opening so that the entire casing may be removed from the vessel through said opening, a heating unit removably secured within the casing having at least its major portion enveloped by the heat exchange fluid, the heating unit causing the heat exchange fluid and the liquid Within the vessel to be heated.

3. The combination as set forth in claim 2, and a plate carried by the outer end of the heater casing, said plate being removably secured to the vessel wall whereby the casing may be detached and removed from the vessel through the vessel wall opening.

4. The combination as set forth in claim 3, and an external flange carried by the heating unit, said fiange being removably secured to the heater casing whereby the heating unit may be detached and removed from the heater casing.

5. The combination with a liquid containing vessel of an internal heater including, aheater unit having upper and lower drums disposed within the vessel and immersed in the liquid contained therein, connections between the drums 

